Piston pump for viscous materials

ABSTRACT

A hydraulically-driven piston pump for viscous materials, especially concrete and similar slurries, comprises a source of a driving liquid, usually water, a cylinder connected to the source and receiving a displacement piston for driving the slurry, and heating means in a bypass at the source at the cylinder or both for preventing freezing of the hydraulic driving fluid.

[ 1 Nov. 11, 1975 United States Patent Schurenberg [5 PISTON PUMP FOR VISCOUS MATERIALS 3.749525 7/1973 Hooper ct 417/343 FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Rudi Schurenberg, Essen Germany Assignee: Firma Torkret Gmbl-I, Essen,

496.115 4/1937 United Kingdomnwnmuun 417/370 German Primary E.\'aminerC. J. Husar Apr' 1974 Assistant E.\aminerO. T. Sessions Appl. No.: 459,114

Attorney, Agent, or FirI71-Kar1 F. Ross; Herbert Dubno [30] Foreign Application Priority Data Apr 6. 1973 ABSTRACT Germany..v.41,,,.,..1.,...73313031U] UNITED STATES PATENTS 3.429.267 2/1969 417/000 7 calms 4 Drawmg figures U.S. Patent Nov. 11,1975 Sheetlof2 3,918,849

U.S. Patent Nov. 11, 1975 Sheet 2 of 2 FIG. 3

I PISTON PUMP FOR VISCOUS MATERIALS FIELD OF THE INVENTION The present invention relates to a piston pump for the displacement of viscous fluids, especiallyslurries such as concrete and, more particularly, to a hydraulically driven piston pump in which the displacement medium or liquid is a fluid whose viscosity increases with lowering temperature or freezes.

BACKGROUND OF THE INVENTION Piston pumps for the displacement of concrete, or other highly viscous materials, such as slurries, have been provided heretofore with at least one cylinder communicating at an end with a source of the slurry and with a discharge duct via a valve arrangement, a piston reciprocable in this cylinder and urged through the latter by a power medium or displacement fluid, especially water or oil.

The use of oil in such applications has the disadvantage that the seals of the system are seldom perfect so that some leakage of oil into the environment, causing a contamination problem, may occur.

However, when water constitutes the hydraulic displacement medium, it is subject to freezing at lower temperatures at the construction site or when the pump is carried on a truck or other vehicle, partly because of the high rate of airflow over the surfaces of the pump and a conduit system.

It has been proposed heretofore to obviate this problem by incorporating into the displacement medium an antifreeze substance capable of reducing the freezing point of the liquid. This is not only expensive but causes a contamination problem of its own should leakage occur.

OBJECTS OF THE INVENTION It is the principal object of the present invention to provide a pump system for the displacement of viscous materials which is free from the aforementioned disadvantages.

Another object of the invention is to provide a piston pump, especially for the displacement of the concrete and like slurries, which can be used without environmental pollution at low temperatures and is effective whether mounted upon a vehicle or at a fixed location.

Still another object of the invention is to improve the low-temperature operability of a slurry-displacement pump at relatively low cost.

SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter are attained, in accordance with the present invention, in a concrete or slurry pump of the piston type which comprises a pump cylinder connectible at one end with a source of the slurry to be displaced and with an outlet therefor and provided with a piston, means for supplying a hydraulic displacement medium susceptible to change in viscosity upon temperature reduction, e.g., water, to the other end of the cylinder, the last-mentioned means including a plurality of passages traversed by the water, duct means establishing a bypass or branch passage for the water parallel to one of the main passages, and electric heating means in the branch passage.

Where the means for feeding the hydraulic displacement medium to the cylinder comprises a pump, a typical branch passage may be established across the inlet and outlet sides of the pump according to the present invention that can be provided with one or more electric heating elements. In addition or as an alternative, a branch passage may be established across a portion of the length of the cylinder to which the hydraulic displacement medium is supplied and can be provided with one or more electric heating elements according to the present invention.

At the construction site, these heating elements can be operated by line voltage or from the normal currentdistribution network or mains while, when the pump is mounted upon a truck or like vehicle, the heating elements can be operated from a special generator driven by the engine of the vehicle.

When required, the heating elements are turned on and a portion of the water flows through the respective branch over the heating elements and is thereby strongly heated and returned to the main water circulation so that the temperature of the hydraulic medium is increased and freezing is prevented. Circulating pumps to maintain the hydraulic medium in motion are thus no longer necessary.

The branches according to the invention can be relatively small, i.e., of small cross section, and they occupy little usable space so that the overall size of the pump assembly is not affected.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a diagrammatic perspective view of a piston pump arrangement embodying the present invention;

FIG. 2 is a detail cross-section of one of the heating devices of the pump of FIG. 1;

FIG. 3 is a view similar to FIG. 2 of the other device; and

FIG. 4 is a diagram of the valve at the end of the cylinders of the piston pump assembly of FIG. 1.

SPECIFIC DESCRIPTION The illustrated piston pump for the displacement of concrete is generally of the type described in Gennan published application No. 2,106,713.

In the drawing, I have shown a piston pump for the displacement of concrete or like slurry materials which comprises a pair of parallel and spacedly juxtaposed displacement cylinders l, 2 lying in a common horizontal plane and mounted on a truck body or positioned fixedly at a construction site. The two cylinders l, 2, are connected to a distributing valve arrangement 4 for selective communication with a hopper or trough 3 receiving the concrete from a mixing station, and with an outlet 5 through which the concrete is conveyed to the site at which it is to be used.

The valve 4, shown in simplified form in FIG. 4, may comprise a slide 40 with openings 4b and 4g communicating with the interior of the trough 3 and can carry the outlet 5 or may have an opening permanently eommunicating therewith. The cylinder 1 opens at la into the valve 4 while the cylinder 2 opens at 2a into the latter. The valve member 4a is provided with a pair of passages 4c and 4d corrununicating with the outlet 5 and respective passages 4e and 4f communicating with the inlets 4b and 43. With the valve member 4a in the posiheating tion illustrated. concrete is admitted through inlet 4g and passage 4f to the cylinder 2 while concrete is displaced from the cylinder 1 via passage 4c to the outlet 5. When the valve member 4a is shifted in the direction A. concrete is permitted to flow from the trough 3 through the inlet 4b into cylinder 1 while concrete is displaced from the cylinder 2 via the passage 4d to the outlet 5.

The pistons within the cylinders l, 2 have not been illustrated but are connected by a cable 6a of a link ar rangement represented generally at 6 and consisting of a housing enclosing the cables and their associated pulleys.

Thus, the cable 60 passes over a pair of idler pulleys 6b at the opposite end of each cylinder 1, 2, along stretches which run parallel to and above the respective cylinders and is diverted around a further pulley 60 between these two stretches. Pistons 6d and 6e in the tubes 6f of the cable arrangement maintain hydraulic isolation of the two cylinders l, 2.

At their powered ends, the cylinders 1, 2 are provided with cylinder extensions 7 connected by ducts 8 and 9 to a two-position. fou r-port valve 10 whose slider or spool is shown at 10a. A pump 11 has its outlet 13 connected to the valve 10 and its inlet 12 communicating with a water tank 14, the valve outlet 20, likewise being connected to the tank 14.

Between the inlet 12 and the outlet 13 of the pump and in parallel with the rest of the control system. there is provided a branch 15 with an electrical heating de vice as represented at 16. This device has been shown in greater detail in FIG. 3 and may comprise a pair of fittings 16a and 16b upon which an insulating sleeve 16(- is threaded to form a heating chamber 160' provided with one or more resistance heating elements or rods 160. The latter are carried on respective plugs 16f threaded into the sleeve 16c and have terminals 16g connectable to line current or a generator as previously noted.

Across a stretch of each section 7 of the respective cylinder 1, 2, there is provided a further branch passage 17 having a heating device 18 therein. While only the heating device is for cylinder 2 has been illustrated, it will be understood that a similar one is provided for cylinder l.

The heating device 18 is shown in greater detail in FIG. 2 and can comprise a fitting 18a threaded into the members 7 and carrying a sleeve 18b into which a lat eral fitting 18c is threaded. The sleeve 18!) may receive a plug 18d carrying a heating rod or element 180 whose terminals 18f are connectable to a source of electric current as previously described. The bypass l7, 18 is disposed upon the underside of the cylinder.

The branches l5, l6 and l7, 18 provide heating pas sages of small cross-section parallel to the main passages and heat a portion of the water diverted along these auxiliary passages strongly before returning the heated portion to the main stream.

As described in the aforementioned patent application. the pump 11 in one position of the 4/2 valve 10 from the tank 14 to one of the cylinders l, 2 whose piston is thereupon displaced toward the outlet 4 to drive tbs slurry therethrough, while dragging the other piston toward the end 7 of the respective cylinder via the cable 4. Upon reversal of the valve 10, the other piston is displaced and the slurry is Forced through the outlet. Respective contactless sensors (limit switches) 21 and 22 detect the advance of the pistons and operate a reversing switch 23 to control the valve 20 to reverse the system.

I claim:

1. A piston pump for the displacement of a slurry. comprising:

at least one cylinder adapted to receive a hydraulically displaceable piston and provided at one end with means for selectively connecting this cylinder to a slurry outlet and a slurry inlet; means forming at least one main passage for water constituting a hydraulic displacement medium connected to the other end of this cylinder and including a pump for displacing said hydraulic medium for shifting said piston and displacing said slurry in through said inlet and out through said outlet;

means forming a branch passage for said displacement medium over at least a portion of the length of said main passage and in parallel therewith; and

at least one electric heating element in said branch passage.

2. The piston pump defined in claim 1 wherein said pump for displacing said hydraulic medium has input and output sides and said branch passage bridges said sides.

3. The piston pump defined in claim 1 wherein a portion of said main passage is formed by a portion of the length of said cylinder at the other end thereof and said branch passage is connected across said portion of said length of said cylinder along the underside thereof.

4. The piston pump defined in claim 3 wherein two such cylinders are provided in parallel spaced-apart orientation in a common horizontal plane and have pistons interconnected by a cable arrangement and their respective other ends, each of said cylinders being provided at its respective other end with a respective branch passage having at least one electric heating element connected therein.

5. The piston pump defined in claim 4 wherein said means forming said main passage includes a water tank, said pump for hydraulic medium having an intake side connected to said water tank and a discharge side, a distribution valve connected to said discharge side and to each of said cylinders at the respective other end, a duct interconnecting said sides of said pump, and an electric heating element in the latter duct.

6. The piston pump defined in claim 5, further comprising means responsive to the movement of said pistons for reversing said valve.

7. The piston pump defined in claim 6, further comprising a common hopper communicating with the respective one end with each of said cylinders and a common outlet extending through said hopper and connectable to the respective one ends of each of said cyl- 

1. A piston pump for the displacement of a slurry, comprising: at least one cylinder adapted to receive a hydraulically displaceable piston and provided at one end with means for selectively connecting this cylinder to a slurry outlet and a slurry inlet; means forming at least one main passage for water constituting a hydraulic displacement medium connected to the other end of this cylinder and including a pump for displacing said hydraulic medium for shifting said piston and displacing said slurry in through said inlet and out through said outlet; means forming a branch passage for said displacement medium over at least a portion of the length of said main passage and in parallel therewith; and at least one electric heating element in said branch passage.
 2. The piston pump defined in claim 1 wherein said pump for displacing said hydraulic medium has input and output sides and said branch passage bridges said sides.
 3. The piston pump defined in claim 1 wherein a portion of said main passage is formed by a portion of tHe length of said cylinder at the other end thereof and said branch passage is connected across said portion of said length of said cylinder along the underside thereof.
 4. The piston pump defined in claim 3 wherein two such cylinders are provided in parallel spaced-apart orientation in a common horizontal plane and have pistons interconnected by a cable arrangement and their respective other ends, each of said cylinders being provided at its respective other end with a respective branch passage having at least one electric heating element connected therein.
 5. The piston pump defined in claim 4 wherein said means forming said main passage includes a water tank, said pump for hydraulic medium having an intake side connected to said water tank and a discharge side, a distribution valve connected to said discharge side and to each of said cylinders at the respective other end, a duct interconnecting said sides of said pump, and an electric heating element in the latter duct.
 6. The piston pump defined in claim 5, further comprising means responsive to the movement of said pistons for reversing said valve.
 7. The piston pump defined in claim 6, further comprising a common hopper communicating with the respective one end with each of said cylinders and a common outlet extending through said hopper and connectable to the respective one ends of each of said cylinders. 